Studies designed to delineate the mechanisms of parvovirus infection and persistence and their possible role in disease have continued using classical virological and immunological as well as modern biochemical technologies. Using our previously developed AAV carrier systems we have determined that multiple copies of the AAV genome integrate into the host cell genome. Further studies using restriction enzyme analysis and heteroduplex mapping should provide insight into the mechanisms of integration and persistence of the AAV genome as well as the processes of excision and productive infection in the presence of helper virus. Investigation will continue of both the structural and virus coded non-virion proteins of the AAV as well as comparative polypeptide and DNA studies of the various plaque and virulence variants of Rat virus, Lu III, MVM, and PVR- we have isolated. These findings, in concert with previous studies of the immunologic specificities of various parvovirus proteins, may well allow the complete mapping of a number of different parvovirus genomes.